Semiconductor device includes semiconductor compounds composed of III-V group elements, such as gallium phosphide (GaP), gallium arsenide (GaAs) or gallium nitride (GaN). The semiconductor device can be optoelectronic semiconductor device such as light-emitting device (LED), laser, photodetector, or solar cell, or can be power device such as switch or rectifier. The LED includes a p-type semiconductor structure, an n-type semiconductor structure and an active structure between the p-type semiconductor structure and the n-type semiconductor structure for emitting light under the principle of transforming electrical energy to optical energy by injecting electrons and holes through the n-type semiconductor structure and the p-type semiconductor structure respectively to the active structure to perform radiative combination and emit light. The research is continued to enhance the conversion efficiency of the optoelectronic semiconductor device.